Pakistani authorities are searching for additional victims in the charred rubble of a luxury hotel in Peshawar, after a suicide bombing there killed at least 15 people late Tuesday.

Another 70 people were wounded in the attack when assailants detonated a truck bomb outside the Pearl Continental Hotel in the capital of North West Frontier Province.

Security camera footage from the hotel was made public Wednesday. It shows a car driving up to a security gate, a burst of gunfire erupting from the car, and then the explosives-filled truck barreling through the checkpoint.

A portion of the hotel was totally destroyed in the blast.

The United Nations confirms at least two of its foreign staffers - a Serbian national and a Philippine national - are among the dead. They are identified as Aleksandar Vorkapic of the U.N. refugee agency and Perseveranda So of the U.N. children's agency.

U.N. Secretary-General Ban Ki-moon also condemned the violence as a "heinous terrorist attack which no cause can justify."

Witnesses say the attackers shot their way past guards and set off a massive blast that ripped through the hotel's side, setting the building on fire.

No one claimed responsibility for the bombing. But Aftab Sherpao, who has served as both provincial chief minister and interior minister, said the attack was clearly designed to pressure the government as it fights Taliban insurgents in the region's Swat Valley.

Pakistani authorities say more than 1,300 militants and about 100 soldiers have been killed since the offensive began in late April.